class Solution:
    def strStr(self, haystack, needle):
        """
        :type haystack: str
        :type needle: str
        :rtype: int
        """
        if not len(needle):
            return 0

        needleLen = len(needle)
        for (i, c) in enumerate(haystack):
            if haystack[i:i + needleLen] == needle:
                return i

        return -1

s = Solution()
print(s.strStr("hello", "ll"))
print(s.strStr("", ""))


